1. Field of the Invention
The present invention relates to a light source unit and a projector which includes the light source unit.
2. Description of the Related Art
In these days, data projectors are used on many occasions as image projection apparatuses which project images including images of screens and video images of personal computers, as well as images based on image data which is stored in memory cards on to a screen. These projectors are such that light emitted from a light source is collected to a display device such as a DMD (Digital Micromirror Device) and a liquid crystal plate for display of a color image onto the screen.
Conventionally, in the mainstream of these projectors, high-intensity discharge lamps are used as light sources. However, in recent years, there have been made many developments and proposals on projectors which use, as a light source, alight emitting diode (LED) or a laser diode, or a device utilizing the organic EL technology or light emission technique using a luminescent material. For example, JP-A-2004-341105 proposes a light source unit having a solid light source as an excitation light source and a luminescent wheel which is made up of a disk-shaped transparent base on which a luminescent material layer is disposed which receives as excitation light ultraviolet light which is emitted from the solid light source and converts it into visible light.
In the light source unit proposed by JP-A-2004-341105, ultraviolet light as excitation light is shone on to the luminescent material layer formed on a surface of the luminescent wheel, and luminescent light of red, green and blue wavelength bands can be emitted from the luminescent wheel. However, the luminous efficiency of the red luminescent material is lower than those of the other luminescent materials, and therefore, in the event that the luminescent material layers are disposed substantially equally in area in the circumferential direction of the luminescent wheel, there is caused a problem that the luminance of red becomes insufficient.